HALIFAX — A Halifax police officer who was demoted for using unnecessary force during a heated traffic stop of a P.E.I. couple has won his appeal and been reinstated as sergeant.

Matthew MacGillivray, a 12-year police veteran, was demoted to constable in January after a disciplinary officer found he had used unnecessary force and engaged in discreditable conduct when he stopped Graham Labonte and Angela Acorn of Belle River, P.E.I.

But in a decision dated Friday, the Nova Scotia Police Review Board overruled that decision, saying that a lawful arrest was made following a reasonable perception of real danger.

During his appeal hearing, MacGillivray said he acted out of concern for his safety during the routine traffic stop that spiralled into an angry videotaped confrontation with the couple, who were on their way to a medical appointment.

The hearing in September heard a recording of a 911 call made by Labonte and saw a 20-second video that features MacGillivray, in uniform, standing behind a visibly upset Acorn, whose hands are behind her back.

As the scene unfolds, MacGillivray points at Labonte, who is operating the camera, and yells, "You are both under arrest!''

Acorn then screams: "You better (explicit) calm down! Calm down!''

From behind the camera, Labonte yells, "I want your name.''

MacGillivray says his name and rank, then pulls off his name tag and throws it in front of Acorn.

"You can have it, take it!'' the officer says as he moves backward, pulling Acorn towards a guardrail.

The video ends abruptly.

In its decision, the review board said the 911 call and video do not tell the full story of the encounter.

"The board recognizes that the 20 second video produced by the complainants and the 911 call, if seen in isolation by the public, could readily leave the impression of discreditable conduct on the part of Const. MacGillvrary," the decision states.

"However, the video is but a tiny segment of the events that occurred, and the 911 call by Mr. Labonte represents only his view of what was happening. These items standing alone do not reflect the reality that a lawful arrest had been made, following a reasonable perception that real danger existed."

Halifax Regional Police said in a statement Friday that MacGillivray's sergeant rank has been reinstated, effective immediately.

The force says under the Police Act of Nova Scotia, a decision of the Police Review Board is final.

The board decision said on Sept. 9, 2015, Labonte and Acorn were travelling to a chronic pain treatment centre in Fall River, N.S., when they passed MacGillivray's marked police vehicle travelling 115 kilometres per hour in a 100 kilometre per hour zone.

After he pulled them over, the review board said, Acorn exited the vehicle, which was "extremely unusual," and was told several times to get back in her vehicle for her own safety.

She was ordered to stop or she would be arrested, the board said. It said the force used during the arrest was not excessive.

"It is common ground that the wrist lock was at the very low end of the spectrum of use of force, and at worse, would cause discomfort only if the subject attempts to pull away," the board said.

It also said MacGillivray attempted to maintain his distance from Labonte.